Machine tool and hydraulic actuating mechanism therefor



May 7, 1935. D. H.'WE ST ET AL 2,000,305 MACHINE TOOL AN-D HYDRAULICAGTUATING MECHANISM THEREFOR I Filed March 16. 1932 I v 7 Sheets-Sheet l,6 WW MI y 1935- D. H. WEST El AL 2,000,805

MACHINE TOOL AND HYDRAULIC ACTUATING MECHANISM THEREFOR Filed March 16,1932 7 Sheets-Sheet 5 lll J06 I .54 as 5 .42 33 a "77 10.9 9, 7 9y L fl3J4 L v 97 r a, a 31 .75? :16- 41 44 7 4.9 F|' .7 6 so" I 3' 60 I 87 J17J08 u H 73 i9.]Q 68 as 91 R N W 73 a4 86 V r uVIIIIIIIIIIIIIIIIIIIIIIIIIIIIIL May 7, 1935. D. H. WEST El AL 2,000,805

- MACHINE TOOL AND HYDRAULIC ACTUATING MECHANISM THEREFOR Filed March16,- 1952 7 Sheets-Sheet III/ 1'1/1 III [III l/II/IIIII III/I I Ieffected and variably controlled. The invention Patented May 7, 1935.

MACHINE TOOL AND HYDRAULIC ACTUAT- ING MECHANISM THEREFOR Donald H.West, Marlboro, and Kenneth C. Monroe, Hudson, Mass, assignors to TheLapointe Machine Tool Company, Hudson, Mass., a corporation of MaineApplication March 16, 1932, Serial No. 599,188

2 Claims.

tools and particularly to hydraulic actuating mechanism by whichsuccessive repeated movements of a reciprocating member in a machinetool may be is applicable to machine tools of various types.

' such as shapers, planers, turret lathes or grinders, in which a tableor other part is repeatedly and automatically reciprocated during theoperation of the machine.

It is the object of our invention to provide improved control devicesfor the hydraulic actuating mechanism in such machine tools, by means ofwhich devices the reciprocating member may be brought to rest withoutshock, and may be quickly but gradually accelerated in direction.

a reverse A further object is to provide, in a machine tool having areciprocating member and hydraulic actuating mechanism therefor, a mainreversing valve and means for varying and controlling the rate of travelof said main reversing valve during the period of reversal of said recmember.

iprocating Our invention further relates to arrangements andcombinations of parts which will be hereinafter described and moreparticularly pointed out in the appended claims.

Preferred forms of the invention are shown in the drawings, in whichline 2--2 in Fig.1;

Fig. 3 is a partial sectional View similar to Fig. 1 but showing theposition of the parts during acceleration to regular working speed;

Fig. 4 is a similar view showing the position of the parts during aworking stroke;

Figs. 5, 6 and '7 are views similar to Figs. 3 and 4 but showingsuccessive positions of the valve mechanism as the reciprocating memberis brought to rest;

Fig. 8 is a similar sectional view showing the position of the partsduring accelerati return movement;

Fig. 9 shows the position of the parts during the regular returnmovement;

on on the Figs. 10, 11 and 12 are similar views showing successive valvepositions as the recip'rocated member is brought to rest at the endoiits return movement;

Figs. 13 and 13 are detail sectional views showing successive positionsof certain speed control valve mechanism during high speed operation andreturn;

Figs. 14 to 17 are diagrammatic sectional views illustrating theoperation of a modified construction;

Fig. 18 is a side elevation of a shaper embodying our invention, and

Fig. 19 is a diagrammatic view of a slight modification oi theconnections to the feeding mechanism.

Referring particularly to Figs. 1 and 18, we have indicated parts of amachine tool, such as a shaper, having a tool support or otherreciprocating member M, slidable in fixed guideways and suitablyconnected through a piston rod 2| to a piston or ram 22 slidable in amain hydraulic cylinder 23. In other machines to which our invention isapplicable, the member M may support the work or a grinding wheel or anyother reciprocated element of the machine.

The main cylinder 23 is connected at its opposite ends by pipes 24 and25 to a reversing valve mechanism R, which preferably comprises a 0311--inder 30 having a valve rod 3! freely slidable therein and provided withspaced piston elements 25 32, 33 and 3B. The ends of the valve rod 3|are slidable in extensions 35 and 36 of the cylinder casing and theseextensions are provided with reduced cylindrical recesses or auxiliarycylinder spaces 31 and 38 closely fitting the rod 3!.

The cylinder 30 is provided with a series or annular ports 40 to $5inclusive. The pipe 24 previously described is connected to the annularport 6! and the pipe 25 to the annular port M. The ports 40 and areconnected through branch pipes #16 and 41 to the discharge or deliverypipe 68 of a hydraulic pump P. The annular ports 52 and #3 are connectedto a common exhaust recess 49 which in turn is connected by a pipe 50 tothe 40 intake of the pump P and by a branch pipe SE to a storage tank T.

The reversing valve piston elements 32, 33 and 3d are slidable in asleeve 53 forming a lining for the cylinder 30. The ports 40, ti, 44 and55 are 45 freely open through the lining 53 into the cylinder 30 but-theports 82 and 43 open into the cylinder 39 through triangular portopenings 55 andfifi in the sleeve or lining 53. The triangular ports 55are clearly shown in section in Fig. 2.

The pump P may be of any desired type which will provide a constantand'positive discharge of oil or other liquid when operated continuouslyin one direction. This pump is continuously rotated from an externalsource of power, such as 5Q a motor X (Fig. 1), and the rate ofdischarge of the pump P may be varied in any convenient manner, as byvarying the speed of the motor X.

An auxiliary gear pump or other low pressure pump G is also preferablydriven from the motor X in any convenient manner, as by a belt 51. Thegear pump G has a supply pipe 50 from the storage tank T and a deliveryor discharge pipe 5| by which liquid under-pressure is delivered to thecasing of a. control valve mechanism 0.

This valve mechanism C comprises a cylinder 10 in which a control valverod H is slidable, said valve rod being provided with spaced pistonelements 12, 18 and 14. The valve rod 1I extends out through one end ofthe casing of the valve mechanism C and may be provided with pairs ofcollars 15 and springs 15, said springs forming a yielding connection toa reversing lever 11 pivoted at 18 and having its upper end projectingbetween dogs and 8I (Figs. 3, 5 and 18) on the reciprocating member M oron some moving part associated therewith or with the piston rod 2|.

The cylinder 10 of the control mechanism C is provided with annularports 82 to 81 inclusive. The ports 84 and are connected through acommon passage 88 to the discharge pipe'5I of the ear pump G. The port82 is connected to an exhaust pipe 80 by which liquid supplied by thegear pump G may be returned to thestorage tank T. The port 81 islikewise connected by a branch pipe iii to the exhaust pipe 90.

A by-pass 82 connects the discharge pipe 6| to the exhaust pipe 80through a relief valve 88, so that the oil supplied by the pump G mayreturn. direct to the storage tank T when the pressure in the pipe 5|exceedsa predetermined limit.

.The port 88 is connected by a pipe to a port st in the side of theauxiliary cylinder space 81' inthe casing extension 85 of the reversingvalve mechanism R. The pipe 85 is also connected by branch pipes 81 and88 to a pipe 80 connected to a port I00 in the outer end of theauxiliary cylinder space 81. An upwardly-opening check valve IIII isprovided in the branch pipe 81 and an ad- Justable needle valve I02 inthe branch pipe 98.

The port 85 is similarly connected through a pipe I05 to a port I05 inthe side of the auxiliary cylinder space 88, and branch pipes I01 andI08 are connected through a pipe I08 and port I I0 to the end of thecylinder space 88. The branch Pipe I01 is provided with anupwardly-opening check valve III and the branch pipe I08 is providedwith an adjustable needle valve II2, all as previously described.

A device for eifecting a. high speed working stroke of the member-Mwithout change in the rate of discharge of the pump P is also provided.This device comprises a cylinder I20 (Fig. 1) connected by pipes I2I andI22 to the pipes 24 and 25 which open into the ends of the main cylinder28. A piston I24 is freely slidable in the cylinder in. Ports in theside of the cylinder I20 are connected by branch pipes I25 and I25 to apipe I21, which latter pipe connects into the pipe 25 above a manuallyoperable shut-off valve I28. A similar shut-off valve I28 is provided inthe branch pipe I25. The operation of this high speed mechanism will behereinafter described.

In the preferred form of our invention; we also provide a fee cylinderI80, connected by branch pipes I8I and I82 to the main cylinder pipeconnections 24;,and 25 respectively. A feed piston I88 is slidable inthe cylinder I80 and is connected by a, piston rod I84 to actuate anydesired feeding mechanism, such as the cross feed mechanism indicated inFig. 18.

Having described the details of construction of the preferred form ofour invention, the method of operation thereof will now be described, itbeing understood that heavy arrows indicate the flow of oil underpressure, and light arrows the flow of oil not under pressure.

Referring to Fig. 3, the parts are shown at the beginning of the firstworking stroke, during which thepiston 22 and piston rod 2I will beaccelerated and will move to the right or in the direction of the arrowa in Fig. 3. It is assumed that the reverse lever 11 has just beenshifted manually from the neutral p ition shown in Fig. 1 to theoperative or working position indicated in Fig. 3. a

Such manual movement of the lever .11 shifts the control valve rod H andpiston elements 12, 18 and 14 in the control valve mechanism C to theright, connecting the pressure pipe 0I through the ports-84 and 88 tothe pipe 95, and connecting the pipe I05 through the ports 85 and 81 andthe branch pipe 8| to the return or exhaust pipe 80.

Oil or other liquid under pressure is thus forced into the auxiliarycylinder space 81 at the righthand end of the valve rod 8| in thereversing valve mechanism R, such oil flowing without restrictionthrough the open check valve III and the branch pipe 81.

This application of pressure in the cylinder space 81 causes the valverod 8| and piston elements 82, 88 and 84 of the reversing piston valveto be moved to the left from neutral position to the position shown inFig. 3. This valve movement is quite slow, however, being resisted bythe oil in the cylinder space 80, which can only escape through theneedle valve II2, as the check valve III is closed by the pressure ofoil thereon.

The reversing piston elements 82, 88 and 84 are thus moved to such aposition that the pump discharge or pressure pipe 48 is connectedthrough the branch pipe 45 and ports 40 and H to the pipe 24 whichconnects to the left-hand end of the main actuating cylinder 28. At thesame time, the pipe 25 connects the right-hand end of the cylinder 28through the ports 44 and 48 to the passage 49 and thence through theexhaust pipe 50 to the storage tank T or to the intake of the pump P.The shut-off valve I28 is assumed to .be closed and the valve I28 isassumed to be open.

It will be noted that the piston element 88 of the reversing valve onlypartially covers the triangular ports 54 when in the acceleratingposition shown in Fig. 3, so that a portion of the oil admitted underpressure through the pipes 48 and 45 escapes through the triangularports-04 and the annular port 42 to the passage 48 and the exhaust pipe50. Consequently the piston 22 and parts associated therewith areaccelerated gradually by oil at reduced pressure, which pressure,however, gradually increases as the reversing valve element 88 continuesits travel to the left under the control of the needle valve 2,gradually closing the ports 54.

-When the reversing valve reaches the final position shown in Fig. 4,the triangular ports 04 are fully covered by the piston element 88, andthe full pressure of the pump P is applied directly against the piston22. In this final position of ,the reversing-valve, its valve rod 8Iuncovers the port 80 for a purpose to be hereinafter described. Any 011delivered from the gear pump G in excess of the small amount required tomove the re- -versing valve is by-passed through the relief valve 33 andcross connection 92 back to the storle tank T.

As soon as pressure is applied in the pipe 24,

this pressure is communicated through the pipe I3I to the cylinder I33and moves the feed piston I33 to the right to eifect movement of anydesired feeding mechanism. In Fig. 18, we have indicated the piston I33as connected by a link I43 to the feed pawl I of a conventional crossfeed mechanism. The feed pawl I may be reversed,

so that movement of the piston I33 to the right working stroke, the dog3| will engage and reverse the position of the lever 11, shifting thelever to the return position indicated in Fig. 5. This shifts the valverod 'II and piston elements I2, I3 and I4 of the control valve mechanismC to the left-hand position shown in Fig. 5, connecting the pressurepipe 3| to the pipe I35 and connecting the pipe 35 to the exhaust pipe33.

Pressure is thus applied through the branch pipe I" and open check valveIII to the cylinder space 33 at the left-hand end of the valve rod 3|,while the right-hand cylinder space 31 is freely connected through theport 93 to the pipe 35, which in turn is connected through the controlvalve mechanism C to the exhaust pipe 90.

There is thus little or no resistance to the movement of the valve rod3| and piston elem nts 32, 33 and 34 to the right until the valve rod 3|has moved far enough to cover the port 33. A portion of each triangularport 54 is thus quickly uncovered, and the pressure of the oil deliveredto the left-hand end of the cylinder 23 is likewise reduced,correspondingly reducing the driving force on the piston 22. continuesto move to the right, however, in part fromthe inertia and momentum ofthe table or other reciprocated member M.

The reversing valve rod 3| and piston elements 32, 33 and 34 thereaftercontinue their movement to the right but at a relatively slow rate, assuch furthermovement is under the control of the needle valve I32. whenthe parts reach the position shown in Fig. 6, the triangular ports 54and 33 are both fully open and there is practically no oil pressure oneither face of the piston 22, but the piston and associated partscontinue to move from inertia-and momentum.

Continued movement of the reversing valve rod 3| and associated pistonparts to' the position shown in- Fig. gradually closes the triangularthe piston 22, as indicated in Fig. 8, thus bringing the reciprocatingparts to rest and initiating a gradually accelerated return movement ofthese reciprocating parts.

The piston 22 When the reversing valve rod 3| reaches its ex-" tremeright-hand position, as indicated in Fig. 9, the triangular ports 55 arefully covered and the piston 22 is moved to the left on its returnstroke at a speed substantially double that of the working stroke, dueto the fact that the cross section of the piston rod 2| is substantiallyone-half of the cross section of the piston 22. The piston rod thusfills one-half of the space in the cylin der 23 at the right-hand "sideof the'piston and leaves only one-half the cylinder volume per unit oflength to be filled by the oil.

As soon as the ports 55 are substantially closed and pressure is builtup in the pipe 25, the feeding piston I33 is movedfto the left, as shownin Fig. 8, thus completing the feeding cycle.

As the piston 22 approaches its left-hand'limit of travel, the dog 30engages the reversing lever I1 and shifts the lever to the workingposition indicated in Fig. 10, which restores the control mechanism tothe position shown in Fig. 3 and applies pressure to the right-handend'of the reversing valve rod 3|, moving the valve rod and associatedpiston elements quickly from the extreme right-hand position shown inFig. 7 to the intermediate position shown in Fig. 10, in which positionthe port I03 is closed.

Continued slow movement of the valve rod 3| and piston elements 32, 33and 34 gradually re- Working pressure .is then built up as in Fig. 3, Y

and the parts thereafter resume the full working position indicated inFig. 4, the cycle of operations being thus completed.

. By the use and operation of our actuating and control mechanism asabove described, the piston '22 and associated parts may be reciprocatedat high speed and may be very quickly brought to rest and reversedwithout shock. The controlled movement of the reversing valve is a veryimportant feature of our invention, and particularly the rapid movementof the valve at the beginning of each reversal,-followed by gradual andcontrolled movement during the latter part of each reversal.

It will be understood that the rate of movement of the reversing valve'in either direction during the latter part of the valve travel isseparately determined; by the setting of the needle valves I32 and H2,and may be varied as desired by changing the setting of these valves.

During the operation of the machine as above described, it has beenassumed that the shut-off valve I23 was open and the valve I23 wasclosed. If it is desired to operate at high speed during the workingstroke, the valve I23 may be closed and the valve I29 opened, in whichcase the operation will be as indicated in Figs. 13 and 13*.

During the working stroke shown in Fig. 13, the pressure of the oil inthe pipe 24 and branch pipe I2| will then shift the piston I24 to theright,

uncovering the port to which the pipe I25 is connected. Oil from theright-hand end of the cylinder 23 will be unable to reach the exhaustpipe 25, as the valve I23 is closed and the branch pipe I23 is blockedoil. by the piston I24 and accordingly this oil fromthe right-hand endof the cylinder 23 must pass through the pipe I2'I, valve I23 and pipeI2I into the pipe 24 through which it is returned to the left-hand endof the cylinder 23. I

Consequently this oil will be added 'to the oil delivered to thecylinder 23 from the pump P and a given amount of oil delivered by-thepump will produce a greater movement of the piston 22.

When the return stroke begins, pressure is ap plied to the pipe 25 andthe piston I23 is shifted to the left, so that the pipe 25 is connectedthrough the branch pipe I22, cylinder I23 and pipes I26 and I21 aroundthe closed valve I23. The piston 22 is thus operated as usual on itsreturn stroke, which will be at the same rate as previously described.

It will be seen therefore that the high speed mechanism increases therate of the-working stroke but does not change the rate of the returnstroke.

.In Figs. 14 to 17 inclusive, we have shown a modified-construction, inwhich the valve rod 3I of the reversing valve mechanism R is extendedthrough the ends of thecylinder extensions I53 and iii and is providedwith coil springs I52 and I53 secured thereon by collars I54. I

The control valve mechanism 0' has a valve rod I63 slidable therein andprovided with spaced piston elements iii and IE2. The control cylinderI33 is also provided with annulanports I34, I33 and I.

The supply or pressure pipe ii is connected to the middle port I65. Theright-hand port I33 is connected by a pipe I10 to the right-handcylinder extension I50 of the reversing valve mechanism R, and theleft-hand port I66 is connected by a'pipe III to the left-hand cylinderextension iii. The reversing mechanism for the control valve C isassumed to be similar to that previously described.

When the piston elements I6I and IE2 of the control valve mechanism 6'are shifted to the working position indicated in Fig. 14, pressurethrough the pipe I'll moves the reversing piston elements 32, 33 and 3|in the valve mechanism R to the left. This movement is at firstrelatively rapid until the parts reach the mid-position shown in Fig. 16butis thereafter at a gradually decreasing 'rate as the spring. I52 iscompressed and offers gradually increased resistance to the movement ofthe reversing valve rod 3I.

Such movement continues, however, 'until the piston elements 32, 33 and33 reach the full speed working position indicated in Fig. 15.

When the working stroke is nearly completed, the valve rod I and pistonelements IiI and I32 in the control mechanism C" are shifted to theposition shown in Fig. 16, applying pressure through the pipe III to thecylinder space in the left-hand extension IiI and connectin theright-hand extension I53 through the pipe I" to the exhaust.

The oil pressin'e at the left-hand end of the reversing valve is thusadded to thepressure of the spring I52 to bring the main reversing.valve .quickly to the mid-position shown in Fig; 16,

ally reduced speed to the return position indicated in Fig. 17.

This form of our invention thus operates in a general way similarly tothe preferred form and possesses many of the advantages thereof. Witheither form of the invention, the speed control and reversal ofreciprocating parts at high speed is very satisfactorily eifected.

The triangular exhaust ports 54 and 55 are very important features ofour invention, as they gradually reduce the rate at which the effectiveby-pass exhaust opening is diminished by continued movement of thereversing valve. This gradual reduction in rate of diminution preventsshock and causes the reciprocating upon reversal.

Having thus described our invention and the advantages thereof, we donot wish to be limited to the details herein disclosed, otherwise thanasset forth in the claims, but what we claim is:-

1. A machine tool comprising a reciprocating member, a main cylinder andpiston connected to move said member, a source of supply of liquid underpressure, connections from said source of liquid supply to each end ofsaid main cylinder, a reversing valve in said connections, a controlvalve for said reversing valve, shifting means for said control valve,means associated with said reciprocating member efiective to actuatesaid shifting means as said member approaches each end of its path oftravel, and means to cause said reversing valve to move relativelyrapidly during the first part of its reversing movement after saidcontrol valve is shifted and to move relatively slowly during the latterpart of its reversing movement, said reversing valve including aport-closing piston and having a pair of exhaust ports in saidconnection for the two ends of said cylinder, said ports being axiallyseparated by a distance not less than theaxial length of saidport-closing piston, whereby one exhaust portwillbe fully uncoveredbefore said piston begins to cover the second exhaust port and whereby agradual deceleration of said piston and associated reciprocating memberwill be eifected.

2. The combination in a machine tool as set forth in claim 1, in whichthe exhaust ports increase progressively in circumferential width towardeach other and in the direction in which they are uncovered by saidpiston.

DONALD H. WEST. KENNETH C. MONROE.

